Chinese Physics C

Testing redshift variation of the X-ray and ultraviolet luminosity relations of quasars

Jiayi Wu, Yang Liu, Hongwei Yu, Puxun Wu

Published:

Abstract:
Quasars serve as important cosmological probes and constructing accurate luminosity relations for them is essential for their use in cosmology. If the coefficients of quasar's luminosity relation vary with redshift, it could introduce biases into cosmological constraints derived from quasars. In this paper, we conduct a detailed analysis of the redshift variation in the X-ray luminosity and ultraviolet (UV) luminosity (

\begin{document}$ L_\mathrm{X} $\end{document}

-

\begin{document}$ L_\mathrm{UV} $\end{document}

) relations of quasars. For the standard

\begin{document}$ L_\mathrm{X} $\end{document}

-

\begin{document}$ L_\mathrm{UV} $\end{document}

relation, we find that the relation coefficients exhibit a strong and linear correlation with redshift, which is not attributable to the selection effect. Additionally, we examine two three-dimensional, redshift-evolving

\begin{document}$ L_\mathrm{X} $\end{document}

-

\begin{document}$ L_\mathrm{UV} $\end{document}

relations and find that the inclusion of a redshift-dependent term does not eliminate the impact of redshift evolution, as the relation coefficients continue to evolve with redshift. Finally, we construct a new

\begin{document}$ L_\mathrm{X} $\end{document}

-

\begin{document}$ L_\mathrm{UV} $\end{document}

relation in which the redshift evolution of the relation coefficients is nearly eliminated. Calibrating the luminosity relations using Hubble parameter measurements, we demonstrate that quasars utilizing our new relation yield effective constraints on cosmological parameters that are consistent with results from Planck CMB data, unlike constraints derived from the standard relation.

Thermodynamics of Barrow Einstein-power-Yang-Mills AdS black hole in the restricted phase space

Yun-Zhi Du, Hui-Hua Zhao, Yang Zhang, Qiang Gu

Published:

Abstract:
Since the quantum gravitational effects Barrow proposed that black hole horizon is "fractalized" into a sphereflake. Based on this issue, in this work we investigate the phase structure and stability of the Einstein-Power-Yang-Mills (EPYM) AdS black holes in the restricted phase space when the black hole event horizon is of the fractal structure. From the thermodynamical first law of the EPYM AdS black hole in the restricted phase space, we find that the mass parameter should be understood as the internal energy. And the Smarr relation of this system in the restricted phase space is not a homogeneous function due to the fractal structure, which is fully different from that of this system in the extended phase space. The corresponding fractal structure can be regarded as a phase transition probe. It is interesting that for the fixed central charge of the EPYM AdS black hole system with the fractal structure there also exists the supercritical phase transition as well as the standard EPYM AdS black hole system. Furthermore the effects of the fractal parameter ∆ and non-linear Yang-Mills parameter γ on the thermodynamical stability of this system are also investigated.

Transfer reaction products in the ⁴⁰Ar + ²³²Th reaction

F. Guan, Z. Y. Zhang, Z. G. Gan, M. M. Zhang, J. G. Wang, M. H. Huang, L. Ma, H. B. Yang, C. L. Yang, Y. H. Qiang, X. L. Wu, Y. L. Tian, J. Y. Wang, Y. S. Wang, S. Y. Xu, Z. Zhao, X. Y. Huang, Z. C. Li, G. Xie, L. Zhu, L. C. Sun, H. Zhou, X. Zhang, J. H. Zheng, H. B. Zhou

Published:

Abstract:
The distribution of nuclei produced in the ⁴⁰Ar + ²³²Th reaction has been studied at the gas-filled recoil separator (SHANS2) at the China Accelerator Facility for Superheavy Elements (CAFE2). The bombardment was carried out at a beam energy of 205 MeV and with the detection system installed at the focal plane. Forty-four isotopes heavier than ²⁰⁸Pb were observed. These isotopes were identified as the transfer reaction (or target-like) products, and their relative cross sections were extracted. Based on the mass distribution of these products, we exclude the possibility that they were produced by fusion-fission reactions, and thus may originate from quasi-fission of the ⁴⁰Ar + ²³²Th reaction.

Nature of X(3872) from recent BESIII data: Considering the universal feature of an S-wave threshold resonance

Xian-Wei Kang, Jin-Zhe Zhang, Xin-Heng Guo

Published:

Abstract:
We analyze the recent data from the BESIII collaboration on the

\begin{document}$ X(3872) $\end{document}

state in the

\begin{document}$ J/\psi\pi^+\pi^- $\end{document}

and

\begin{document}$ D^0\bar{D}^0\pi^0 $\end{document}

decay channels. The quantum number and mass of the

\begin{document}$ X(3872) $\end{document}

state allow us to exploit the universal feature of the very near-threshold

\begin{document}$ D\bar D^* $\end{document}

scattering in the S wave. The analysis of

\begin{document}$ J/\psi\pi^+\pi^- $\end{document}

data and

\begin{document}$ D^0\bar{D}^0\pi^0 $\end{document}

data separately as well as the combined analysis of these data together, all support the conclusion that

\begin{document}$ X(3872) $\end{document}

is an extremely weakly bound charm meson molecule.

Neutrino transition magnetic moment in the U(1)_XSSM

Long Ruan, Shu-Min Zhao, Ming-Yue Liu, Xing-Yu Han, Xi Wang, Xing-Xing Dong

Published:

Abstract:
This paper investigates the neutrino transition magnetic moment in the

\begin{document}$ U(1)_X $\end{document}

SSM.

\begin{document}$ U(1)_X $\end{document}

SSM is the

\begin{document}$ U(1) $\end{document}

extension of Minimal Supersymmetric Standard Model (MSSM) and its local gauge group is extended to

\begin{document}$ SU(3)_C\times SU(2)_L \times U(1)_Y\times U(1)_X $\end{document}

. To obtain this model, three singlet new Higgs superfields and right-handed neutrinos are added to the MSSM, which can explain the results of neutrino oscillation experiments. The neutrino transition magnetic moment is induced by electroweak radiative corrections. By applying effective Lagrangian method and on-shell scheme, we study the associated Feynman diagrams and the transition magnetic moment of neutrinos in the model. We fit experimental data for neutrino mass variances and mixing angles. Based on the range of data selection, the influences of different sensitive parameters on the results are analysed. The numerical analysis shows that many parameters have an effect on the neutrino transition magnetic moment, such as

\begin{document}$ g_X $\end{document}

,

\begin{document}$ M_2 $\end{document}

,

\begin{document}$ \mu $\end{document}

,

\begin{document}$ \lambda_H $\end{document}

and

\begin{document}$ g_{YX} $\end{document}

. For our numerical results, the order of magnitude of

\begin{document}$ \mu_{ij}^M/\mu_B $\end{document}

is around

\begin{document}$ 10^{-20} $\end{document}

\begin{document}$ \sim $\end{document}

\begin{document}$ 10^{-19} $\end{document}

.

Search for the Cabibbo-suppressed decays Λ_c⁺ → Σ⁰K⁺π⁰ and Λ_c⁺ → Σ⁰K⁺π⁺π⁻

M. Ablikim, M. N. Achasov, P. Adlarson, X. C. Ai, R. Aliberti, A. Amoroso, Q. An, Y. Bai, O. Bakina, Y. Ban, H.-R. Bao, V. Batozskaya, K. Begzsuren, N. Berger, M. Berlowski, M. Bertani, D. Bettoni, F. Bianchi, E. Bianco, A. Bortone, I. Boyko, R. A. Briere, A. Brueggemann, H. Cai, M. H. Cai, X. Cai, A. Calcaterra, G. F. Cao, N. Cao, S. A. Cetin, X. Y. Chai, J. F. Chang, G. R. Che, Y. Z. Che, G. Chelkov, C. Chen, C. H. Chen, Chao Chen, G. Chen, H. S. Chen, H. Y. Chen, M. L. Chen, S. J. Chen, S. L. Chen, S. M. Chen, T. Chen, X. R. Chen, X. T. Chen, Y. B. Chen, Y. Q. Chen, Z. J. Chen, Z. K. Chen, S. K. Choi, X. Chu, G. Cibinetto, F. Cossio, J. J. Cui, H. L. Dai, J. P. Dai, A. Dbeyssi, R. E. de Boer, D. Dedovich, C. Q. Deng, Z. Y. Deng, A. Denig, I. Denysenko, M. Destefanis, F. De Mori, B. Ding, X. X. Ding, Y. Ding, Y. X. Ding, J. Dong, L. Y. Dong, M. Y. Dong, X. Dong, M. C. Du, S. X. Du, Y. Y. Duan, Z. H. Duan, P. Egorov, G. F. Fan, J. J. Fan, Y. H. Fan, J. Fang, S. S. Fang, W. X. Fang, Y. Q. Fang, R. Farinelli,

Published:

Abstract:
Utilizing 4.5

\begin{document}$ \text{fb}^{-1} $\end{document}

of

\begin{document}$ e^+e^- $\end{document}

annihilation data collected at center-of-mass energies ranging from 4599.53 MeV to 4698.82 MeV by the BESIII detector at the BEPCII collider, we search for the singly Cabibbo-suppressed hadronic decays

\begin{document}$ \Lambda_{c}^{+}\to\Sigma^{0} K^{+}\pi^{0} $\end{document}

and

\begin{document}$ \Lambda_{c}^{+}\to\Sigma^{0}K^{+} \pi^+ \pi^- $\end{document}

with a single-tag method. No significant signals are observed for both decays. The upper limits on the branching fractions at the 90% confidence level are determined to be

\begin{document}$ 5.0\times 10^{-4} $\end{document}

for

\begin{document}$ \Lambda_{c}^{+}\to\Sigma^{0} K^{+}\pi^{0} $\end{document}

and

\begin{document}$ 6.5\times 10^{-4} $\end{document}

for

\begin{document}$ \Lambda_c^{+}\to\Sigma^0K^{+}\pi^{+}\pi^{-} $\end{document}

.

Explanation of the nature of the island of inversion exhibited by ³²Mg at the Hartree-Fock-Bogoliubov level and beyond

Yong Peng, Jia Liu, Jing Geng, Yi Fei Niu, Wen Hui Long

Published:

Abstract:
This work presents an explanation of the nature of the island of inversion exhibited by the unstable nucleus ³²Mg, through the applications of the axially deformed relativistic Hartree-Fock-Bogoliubov (D-RHFB) and the configuration-interaction relativistic Hartree-Fock (CI-RHF) models, which correspond to the Hartree-Fock-Bogoliubov level and beyond, respectively. Using the same Lagrangian PKA1, the D-RHFB and CI-RHF models demonstrate an excellent agreement with experimental data for the ground-state deformation and the low-lying excitation energies of ³²Mg. Furthermore, a new insight into the nature of the island of inversion is implemented from the breaking of the pseudo-spin symmetry (PSS), in addition to the cross-shell excitation, both of which are essential to give rise to a stable deformation and a rotational collectivity for ³²Mg. In particular, the exchange degrees of freedom, like the ρ-tensor coupling in PKA1, are illustrated to play a substantial role in determining the configuration interactions and the binding of the nucleus.

Study of the true ternary fission for ²⁴⁸Cf isotope in the equatorial and the collinear geometries

M. R. Pahlavani, M. Saeidibabi

Published:

Abstract:
This study presents a comprehensive investigation of the true ternary fission for

\begin{document}$ ^{248}\text{Cf} $\end{document}

isotope. Using the Three-Cluster Model (

\begin{document}$ \text{TCM} $\end{document}

) based on the

\begin{document}$ \text{WKB} $\end{document}

approximation, detailed calculations were performed for all possible fragment configurations, considering the equatorial and the collinear geometries. The fragment charge numbers (Z) were systematically filtered within the range

\begin{document}$ Z = 20 $\end{document}

to

\begin{document}$ Z = 52 $\end{document}

, and all combinations were examined for three positional arrangements: the fragments

\begin{document}$ A_{1} $\end{document}

,

\begin{document}$ A_{2} $\end{document}

, and

\begin{document}$ A_{3} $\end{document}

occupying the middle position in the collinear geometry. For each combination, key quantities were calculated, including driving potential (

\begin{document}$ \text{V - Q} $\end{document}

), penetration probability (P), relative yield Y, decay constant (λ), and half-life (

\begin{document}$ T_{\frac{1}{2}} $\end{document}

). The selection of optimal fragment combinations was based on the higher penetration probability or the minimum driving potential, ensuring a systematic approach to identifying the most favorable fission configurations. Redundancy from permutations of

\begin{document}$ Z_{1} $\end{document}

,

\begin{document}$ Z_{2} $\end{document}

, and

\begin{document}$ Z_{3} $\end{document}

was eliminated by treating them equivalently. The results highlight the significant influence of fragment geometry and the nuclear structure, particularly shell effects, on the fission dynamics. This work provides new insights into the complex mechanisms of the true ternary fission, contributing to the broader understanding of nuclear stability and fragment distributions in such processes. Furthermore, the effects of fragments permutations, geometries and neutron emission through fission process are the novelty of this study relative to the similar researches.

Nuclear matter and neutron star properties constrained by CREX results and astrophysical constraints: A covariance study

Sunil Kumar, Vikesh Kumar, Pankaj Kumar, Raj Kumar, Shashi K Dhiman

Published:

Abstract:
The ground state properties of finite, bulk matter and neutron stars are investigated using the proposed effective interaction (HPU4) for the relativistic mean field model (RMF), that incorporates self and cross-couplings of σ, ω, and ρ mesons with nucleon. This interaction has been constructed by fitting data on finite nuclei's binding energies and charge radii, neutron skin (

\begin{document}$ \Delta r_{\text{np}} $\end{document}

) of

\begin{document}$ ^{48} {\rm{Ca}}$\end{document}

nucleus, and astrophysical observations of neutron stars' maximum masses.

\begin{document}$ \Delta r_{\text{np}} $\end{document}

(

\begin{document}$ ^{48} {\rm{Ca}}$\end{document}

) = 0.146±0.019 fm is achieved with soft symmetry energy (

\begin{document}$ J_{0} $\end{document}

= 27.91±1.31 MeV) and its corresponding slope (

\begin{document}$ L_{0} $\end{document}

= 42.85±14.26 MeV) at saturation density. An equation of state (EoS) having a composition of β- equilibrated nucleonic and leptonic matter is computed. The nuclear matter and neutron star properties are also analyzed for this interaction and agree well with the astrophysical observations, such as the NICER and GW170817 events. We also perform the statistical analysis to estimate the theoretical errors in coupling parameters, and neutron star observables, and to find the correlation coefficients. It is observed that neutron skin of

\begin{document}$ ^{208} {\rm{Pb}}$\end{document}

and

\begin{document}$ ^{48} {\rm{Ca}}$\end{document}

is strongly correlated and shows a strong dependence on

\begin{document}$ J_{0} $\end{document}

,

\begin{document}$ L_{0} $\end{document}

, and curvature of symmetry energy,

\begin{document}$ K_{\text{sym}} $\end{document}

as suggested from their correlations. A strong correlation of

\begin{document}$ R_{1.4} $\end{document}

with ρ-meson-nucleon coupling quantified by term

\begin{document}$ g_{\rho N} $\end{document}

, and mixed interaction terms,

\begin{document}$ \sigma\rho_{\mu}\rho^{\mu} $\end{document}

and

\begin{document}$ \sigma^{2}\rho_{\mu}\rho^{\mu} $\end{document}

is also observed.

Neutron-proton isovector pairing correlations treatment in heated nuclei within the path integral formalism

M. Fellah, N.H. Allal, M.R. Oudih

Published: , doi: 10.1088/1674-1137/adc4cb

Abstract:
A method for the treatment of the neutron-proton (np) isovector pairing correlations at finite temperature is developed within the path integral formalism. It generalizes the recently proposed model using a similar approach in the pairing between like-particles case. The pairing terms in the total Hamiltonian are written in a square form in order to facilitate the use of the Hubbard-Stratonovitch transformation. The expression for the partition function of the system is then established. The gap equations, as well as the expressions for the energy, the entropy and the heat capacity of the system are deduced. As a first step, the formalism is numerically applied to the schematic Richardson model. As a second step, the method is applied to nuclei such as

\begin{document}$ N=Z $\end{document}

using the single-particle energies of a deformed Woods-Saxon mean-field. The variations in the gap parameters, the excitation energy and the heat capacity are studied as functions of the temperature. It is shown that the overall behavior of these quantities is similar to their homologues in the standard FTBCS model. We note in particular the existence of critical temperatures beyond which the pairing vanish. Moreover, it appears that in the framework of the present approach, the pairing effects persist beyond the critical temperatures predicted by the FTBCS model in the pairing between like-particles case or its generalization in the np pairing case.

Charged Black Holes in the Kalb-Ramond Background with Lorentz Violation: Null Geodesics and Optical Appearance of a Thin Accretion Disk

K. TAN, X.G. Lan

Published:

Abstract:
In this paper, we investigate the optical appearance of a charged black hole in the Kalb-Ramond background, incorporating a Lorentz-violating parameter

\begin{document}$ l=0.01 $\end{document}

. By analyzing the null geodesics, we derive the photon sphere, event horizon, effective potential, and critical impact parameters. We then employ a ray-tracing technique to study the trajectories of photons surrounding a thin accretion disk. Three different emission models are considered to explore the observed intensity profiles of direct rings, lensing rings, and photon sphere. By comparing these results with those of the standard Reissner-Nordström black hole (

\begin{document}$ l=0 $\end{document}

) and the Kalb-Ramond black hole with different values of Lorentz-violating parameter (specifically,

\begin{document}$ l=0.05 $\end{document}

and

\begin{document}$ l=0.1 $\end{document}

respectively), we find that the Lorentz symmetry breaking will lead to a decrease in the radii of the photon sphere, the event horizon, and the innermost stable circular orbit. Consequently, this makes the detection of these black holes more challenging.

Gravitational losses for the binary systems induced by the next-to-leading spin-orbit coupling effects

Hao Zhang, Wei Gao, Guansheng He, Siming Liu, Huanyu Jia, Wenbin Lin

Published:

Abstract:
The orbital energy and momentum of the compact binary systems will loss due to gravitational radiation. Based on the mass and mass-current multipole moments of the binary system with the spin vector defined by Bohé et al. [Class. Quantum Grav. 30, 075017 (2013)], we calculate the loss rates of energy, angular momentum and linear momentum induced by the next-to-leading spin-orbit effects. For the case of circular orbit, the formulations for these losses are given in terms of the orbital frequency.

Nuclear stability and the ratio of kinetic to potential energy

Ke-Hu Wang, Zhang-Ya Wang, Ning Wang, Min Liu

Published:

Abstract:
Based on the Skyrme energy density functional, we systematically analyze the ratio

\begin{document}$ T/U $\end{document}

between the kinetic and potential energies for even-even nuclei at their ground states. We note that the nuclei with maximal value of

\begin{document}$ T/U $\end{document}

are generally stable nuclei for a certain isobaric chain with

\begin{document}$ Z\le 82 $\end{document}

. The known magic numbers can be more evidently observed from the ratio

\begin{document}$ T/U $\end{document}

comparing with nuclear binding energy, particularly for the isobaric chains with semi-magic nuclei. Combining the predicted binding energies and the ratios

\begin{document}$ T/U $\end{document}

from the Skyrme Hartree-Fock-Bogoliubov (HFB) code HFBTHO with parameters set UNEDF0, the possible magic numbers in super-heavy mass region are simultaneously studied. The neutron magic number

\begin{document}$ N=184 $\end{document}

can be clearly observed from the calculated values of

\begin{document}$ T/U $\end{document}

and the extracted microscopic energies of nuclei.

Exploring Shape (phase) Evolution in even-even ^126−136Ba

Jie Yang, Xin Guan, Rong-Xin Nie, Hua-Lei Wang, Feng Pan, Jerry P. Draayer

Published:

Abstract:
The evolution of nuclear shape and rotational behavior along the yrast line in even-even

\begin{document}$ ^{126-136} {\rm{Ba}}$\end{document}

has been systematically investigated using pairing self-consistent Woods-Saxon-Strutinsky calculation combined with the total Routhian surface (TRS) method in the (

\begin{document}$ \beta_2, \gamma, \beta_4 $\end{document}

) deformation space. Empirical laws are applied to evaluate nuclear ground-state properties, revealing a shape evolution from axially deformed to the non-axial vibrational configuration in even-even

\begin{document}$ ^{126-136} {\rm{Ba}}$\end{document}

isotopes. Particularly, an extreme γ-unstable shape is predicted in

\begin{document}$ ^{130} {\rm{Ba}}$\end{document}

. The shape transition of the ground state in these nuclei is confirmed by the TRS calculations. In addition, the evolution of the nuclear shape in high spin states with varying rotational axes associated with rotation around the medium, long, and short axes is illustrated by the TRS calculations. This variation is further characterized by the alignment of the

\begin{document}$ \pi(h_{11/2})^2 $\end{document}

and

\begin{document}$ \nu(h_{11/2})^2 $\end{document}

configurations, highlighting a preference for non-collective oblate/triaxial shapes with

\begin{document}$ \gamma > 0^{\circ} $\end{document}

and collective oblate/triaxial shapes with

\begin{document}$ \gamma < 0^{\circ} $\end{document}

, respectively.

Black holes in general relativity coupled with nonlinear electrodynamics surrounded by perfect fluid dark matter: Thermodynamics, particle motion and black hole shadow

Bekzod Rahmatov, Muhammad Zahid, Saeed Ullah Khan, Javlon Rayimbaev, Inomjon Ibragimov, Zukhriddin Yuldoshev, Adilbek Dauletov, Sokhibjan Muminov

Published:

Abstract:
This study explores black holes in General Relativity (GR) coupled with nonlinear electrodynamics (NED) in the presence of perfect fluid dark matter (PFDM). We derive a singular black hole solution and investigate its thermodynamic properties, including black hole temperature, entropy, and specific heat capacity of the black hole spacetime. The analysis of energy conditions reveals deviations from standard GR, with PFDM affecting the weak and strong energy conditions. The study further examines the impact of NED and PFDM on the innermost stable circular orbit (ISCO), demonstrating that PFDM shifts the ISCO radius and that combined effects of NED and PFDM field parameters sufficiently influence orbital stability. Our analysis of the black hole shadow reveals that PFDM increases the shadow radius while a higher charge reduces it, leading to modifications in potential astrophysical observables. The thermodynamic behavior of the black hole exhibits phase transitions marked by changes in heat capacity, indicating possible stability regimes. Moreover, we also derive equations for black hole shadow size and study the spacetime effects on the shadow. These results provide a framework for testing alternative gravity theories and understanding the role of exotic matter in strong gravitational fields. Finally, we compare the constraints on NED and PFDM field parameters derived from our black hole model with the Event Horizon Telescope (EHT) observations of M87* and Sgr A*, providing observational limits on deviations from General Relativity.

Note on single-trace EYM amplitudes with MHV configuration

Zhirun Li, Yi-Jian Du

Published:

Abstract:
In the maximally-helicity-violating (MHV) configuration, tree-level single-trace Einstein-Yang-Mills (EYM) amplitude with one and two gravitons have been shown to satisfy a formula where each graviton splits into a pair of collinear gluons. In this paper, we extend this formula to more general cases. We provide a general formula which expresses tree-level single-trace MHV amplitudes in terms of pure gluon amplitudes, where each graviton turns into a pair of collinear gluons.

Relativistic Hartree-Fock model for axial-symmetric nuclei with quadruple and octupole deformations

Yong Peng, Jing Geng, Wen Hui Long

Published:

Abstract:
Axially quadruple-octupole deformed relativistic Hartree-Fock (O-RHF) model with density-dependent meson-nucleon couplings is developed in this work, in which the reflection symmetry is not preserved anymore and the integro-differential Dirac equations are solved by expanding the Dirac spinor on the spherical Dirac Woods-Saxon basis. The reliability of the newly developed O-RHF model is illustrated by taking the octupole nucleus